Apparatus for corrugating metal tubing



July 12, 1966 w. K. GRUETTER ETAL 3,260,033

APPARATUS FOR CORRUGATING METAL TUBING 6 Sheets-Sheet 1 Filed Sept. 20, 1963 July 12, 1966 w. K. GRUETTER ETAL 3,260,038

APPARATUS FOR CORRUGATING METAL TUBING 6 Sheets-Sheet 2 Filed Sept. 20, 1963 July 12, 1966 w. K. GRUETTER ETAL 3,

APPARATUS FOR CORRUGATING METAL TUBING 6 Sheets-Sheet 3 Filed Sept. 20, 1963 FIG.4.

July 12, 1966 w. K. GRUETTER ETAL 3,260,088

APPARATUS FOR CORRUGATING METAL TUBING 6 Sheets-Sheet 4 Filed Sept. 20, 1963 July 12, 1966 w. K. GRUETTER ETAL 3,260,038

APPARATUS FOR CORRUGATING METAL TUBING 6 Sheets-Sheet 5 Filed Sept. 20, 1963 6 Sheets-Sheet 6 l I I 1 I 1 I l l l I I I I l I l I I 1 1 I W. K. GRUETTER ETAL APPARATUS FOR CIORRUGATING METAL TUBING July 12, 1966 Filed Sept. 20, 1963 United States Patent 3,260,088 APPARATUS FOR CORRUGATING METAL TUBING Werner K. Gruetter, Tenafly, George J. Gendron, Oradell, Harold M. McCall, Fairlawn, and Henry A. Nelson Holland, Ridgewood, N J assignors to Raymond InterrJiational Inc., New York, N.Y., a corporation of New ersey Filed Sept. 20, 1963, Ser. No. 310,229 14 Claims. (Cl. 72-103) This invention relates to apparatus for corrugating sheet metal tubing.

While the apparatus of the invention is useful for corrugating metal tubing of a variety of types and sizes, it is particularly adapted for applying helical corrugations to tubing having fairly large diameters, such for example as used for forming shells for concrete piles and for forming tubing for culverts or other forms of conduits. Usually such tubing is initially formed by curving an elongated strip or sheet of material into tubular form, either by helically winding the strip into tubular shape, or by shaping same With a longitudinal seam, the edges of the metal in either case being welded together, such as by the use of high frequency electrical current. However, the present invention is adapted, of course, for use in corrugating tubing made by other methods. The invention is also well adapted for use in forming corrugations on the tubing comprised of a single turn or thread, or, if preferred, the corrugating rollers or dies may be so shaped as to form corrugations comprised of a plurality of turns or threads, for instance a double thread, as is sometimes preferred in forming concrete pile shells.

Preferably in accordance with the invention, a rigid mandrel is provided, supported at one end and preferably free at the other end, and on which lengths of the tubing to be corrugated are slid into place thereon. Internal and external corrugating rollers are provided at one side of the mandrel, and at or near the free end thereof to engage the tube metal internally and externally, at What will be herein referred to as the corrugating area, at which the rollers apply the desired corrugations while the length of tubing and the mandrel are moved longitudinally with respect to each other. Preferably the external corrugating roller is in the form of a ring encircling the tubing and driven by a source of power to rotate along a plane positioned at an angle with respect to the axis of the tubing corresponding approximately to the pitch angle of the desired corrugations, and in case it is preferred that the mandrel be stationary, this ring, as driven, serves to impart force having components for rotating and advancing the tubing longitudinally, while the internal corrugating roller may be in the form of an idler roller, preferably mounted in a fixed position adjacent the free end of the mandrel.

Since the external corrugating roller is preferably in the form of a ring encircling the tubing, it will, of course, be of a diameter greater than that of the tubing and accordingly same may be brought into approximately tangential relationship to the exterior surface of the tubing in a manner such that there will be a considerable area of contact between the two, whereby the corrugations are imparted to the tube metal rather gradually, with avoidance of abrupt bending or scuffing of the metal. Also the internal corrugating roller is preferably of a diameter as great as a major part of the internal diameter of the tubing, so that this roller also will tangentally engage the tube metal over a fairly extended area, similarly with avoidance of scuffing or improperly distorting the metal.

As above noted, the corrugating rollers engage the tube metal at an area to one side of the mandrel and 3,260,088 Patented July 12, 1966 consequenti-ally forces established during the corrugating action will ten-d powerfully to react against the mandrel at or near its free or generally unsupported end. Accordingly, to prevent deflection or bending of the mandrel, supporting means is preferably provided on the opposite side of the mandrel to resist such force which would otherwise tend to deflect the mandrel. This is especially necessary in the case of large tubing having a substantial wall thickness. Such supporting means on said opposite side of the mandrel preferably takes the form of an internal idler roller mounted on the mandrel, and an external rotatable ring encircling the tubing for tangentially engaging the tubing at the area where the internal supporting roller is located and shortly prior to the corrugated areas. Such rotating supporting ring, as mounted in suitable bearings, thus applies pressure to the tubing, which in turn applies pressure to the internal supporting roller for resisting the bending forces on the mandrel.

In cases where the tube metal is of substantial strength and thickness, it is desirable to apply rotational driving force to the above-mentioned rotatable supporting ring so that it will contribute forces having components for rotating and longitudinally advancing the tubing and supplemental to such forces as applied :by the corrugating ring, thereby avoiding concentrating the forces entirely at the corrugating area, which might there cause scuffing or undue distortion of the metal. However, the application of rotational and advancing forces to the tubing at two different areas involves the problem of insuring that the forces at the two areas Will be such as to tend to rotate and advance the tubing at the same speed; otherwise the forces at one of the areas may more or less resist those applied at the other, with consequent scuffing or distortion of the metal. This prob lem involves the difiiculty that the effective diameter of the tubing where the forces are applied at the corrugating area Will be somewhat different from the diameter at the area where the supporting rollers are applied, and which has not yet been corrugated. It has been found, however, that this difficulty may be overcome either by using a driven corrugating ring and a driven supporting ring of different and appropriate diameters, or by rotating same at different speeds, or by suitably adjusting the angles of the planes along which they rotate.

In corrugating metal tubing, the formation of the corrugations necessarily results in some stretching of the metal in radial directions, as well as some twisting forces on the tubing, and in order to insure that the finished corrugated tubing will be of predetermined lengths, it is important that the degree of such stressing be uniformly controlled and predetermined, and the solution to this problem involves further aspects of the present invention.

Various further and more specific objects, features and advantages of the invention Will appear from the description given below, taken in connection with the accompanying drawings, illustrating by way of example a preferred form of the invention.

In the drawings:

FIG. 1 is a plan View of a preferred form of the apparatus in one condition of adjustment;

FIG. 2 is a side view of the same;

FIG. 3 is an enlarged plan view of the apparatus which is shown in full lines in a condition such as when originally assembled, same being shown in outline by dotted lines after certain adjustments;

IFIG. 4 is a transverse sectional line 44 of FIG. 3;

FIG. 5 is a side view taken along line 5-5 of FIG. 3;

FIG. 6 is a horizontal cross-sectional view taken substantially along line 6-6 of FIG. 4;

View taken along FIG. 7 is a side view of the mandrel head assembly taken substantially along line 77 of FIG. 6 and showing in section portions of the corrugating and supporting rm s;

FIG. 8 is a horizontal sectional view taken substantially along line 8--8 of FIG. 7; and

FIGS. 9 and 10 are sectional views taken along lines 99 and 1010 of FIG. 7.

Referring now to the drawings in further detail, as shown in FIG. 1, preferably a rigid stationary mandrel is provided as at 12, suitably fixed and rigidly supported at one end .13 and carrying-on its free end a mandrel head assembly 14 as hereinafter further described. Lengths of sheet metal tubing initially having smooth walls and which are to be corrugated, are slid onto the mandrel 12 to the position indicated by dotted lines at 15 and as the apparatus corrugates same, such tubing is advanced in the direction of the arrow past the mandrel head assembly 14 and off the mandrel, to other suitable supporting or conveyor means.

As further shown in FIGS. 1 and 2, corrugating means are provided at 16 encircling the workpiece, and supporting means are provided as at .17 also encircling the workpiece shortly in advance of the corrugating means. The corrugating means and supporting means respectively are driven as -by motors 18 and 19, which, together with supporting bases therefor and the corrugating and supporting means associated therewith, comprise assemblies which are adjustable to angles with respect to the axis of the mandrel, such as shown in FIG. 1.

Referring now to FIGS. 6, 7 and 8, the mandrel head assembly 14 comprises a corrugating ring or roller 20 mounted to rotate about the mandrel head 14 internally of the tubular workpiece 15, and a smooth-surfaced supporting ring or roller 21 also mounted rotatably on the mandrel head 14 and adapted to engage, in a manner hereinafter described, the interior surface of a smoothwalled portion of the tubing prior to its corrugation. At the location of the corrugating ring 20, the tubular workpiece is surrounded by a rotating corrugating ring 22 and at the location of the supporting roller 21, the workpiece is surrounded by a supporting ring 23 having a smooth interior surface.

The corrugating roller and the corrugating ring 22 are mounted to extend along a plane at What will be termed a helix angle with respect to the axis of the mandrel and, in a typical case by way of example, as here illustrated, this helix angle may be a little over 4.5", the exact preferred angle being subject to calculation as hereinafter explained. The supporting roller 21 and the supporting ring 23 also are located along a plane,-

which will have an opposite helix angle (preferably a slightly larger angle than that of the corrugating means) and which also may be calculated as hereinafter described. The corrugating roller 20 is formed with a plurality of circumferential grooves as at 24 and the corrugating ring 22 is similarly internally formed with a plurality of corresponding corrugating ridges 25. In the example shown, these grooves and ridges are shaped and positioned to form double thread corrugations on the tubular workpieces. The diameters of the elements 20 and 2 2, and the locations and angular positions thereof, are such that, as shown in the cross-sectional View of FIG. 10, the roller 20, along its lower peripheral portions as at 26, will internally engage the workpiece, and at this region, the corrugating ring 22 will externally engage the workpiece at the region 26, the engagements in both cases being substantially tangential and of such a wide extent that, as this ring and roller cooperate in corrugating the tubing, they will do so without abruptly scuffing or objectionably marring the metal. However, in so doing, considerable upward pressure will be applied to the mandrel head, and thus to retain the mandrel and mandrel head against upward deflection, the supporting ring 23 and supporting roller 21 (as shown in FIG. 9) will engage the tubular workpiece at a region indicated at 27, this engagement also being quite extensive tangentially of the interior and exterior surfaces of the tubing at a location where such surfaces are still smooth. The manner in which the parts engage the work to impart the corrugations is also shown at the lower righthand portion of FIG. 7 at 26, 26, and the manner in which the parts engage the work to provide the reaction for supporting the mandrel against defiexion, is also shown at 27 in FIG. 7. It will be appreciated that, in adjusting the helix angles of the corrugating means and of the supporting means respectively, same are turned to opposite angles about vertical axes, such as indicated by the section lines Ill-r10 and 9-9 as shown in FIG. 7. The corrugating and supporting rings and rollers are of such diameters that, as shown in the horizontal sectional view of FIG. 8, they will not press against the tubular workpiece at the region shown by this sectional view.

As further shown in FIGS. 7-10 inclusive, the corrugating roller 20 and the supporting roller 21 may be mounted on roller bearing assemblies, as at 30 and 31 respectively, encircling respectively reduced portions 32 and 33, on a central shaft 34 which carries the mandrel headpiece 14, the shaft 34 having a socket as at 35 for receiving the forward end of the mandrel 12 on which the mandrel headpiece may be removably retained as by a screw or pin 36.

Referring now more particularly to FIG. 6, the corrugating ring 22 may be fixed within, and rotated with an annular supporting ring 37, mounted with annular ball bearing assemblies as at 38, which in turn are mounted within a relatively fixed frame means 39. The annular supporting ring 37 has annular sprocket means 40 affixed around its periphery, which-sprocket means (see also FIG. 4) is engaged by a sprocket chain 41 driven by another sprocket as at 42, which in turn (as shown also in FIG. 5 is mounted upon a shaft 43 with a coupling 44 connecting same to the drive motor 18 for the corrugating means. The lower reach of the sprocket chain 41 may (as shown in FIGS. 4 and 6) pass over a small idler sprocket 45.

As best shown in FIGS. 3 and 5, the entire assembly comprised of the motor 18, the corrugating ring and the supporting and driving means therefor, including a base or supporting means 50, may be adjusted about a vertical axis (indicated'at 51 in FIG. 3) so that this assembly can be adjusted to the predetermined or calculated helix angle. This may be accomplished by adjusting screw rods, as indicated at 52 and 53 in various of the figures, and, after such adjustments, the base may, as indicated in FIG. 3, be clamped in position as by bolts 54 passing through slots 55 in the base 50, and thence into the base 56, which supports the entire head end of the machine.

In order to permit a tubular workpiece to be readily slid onto the mandrel 12 without being engaged at its lower side by the corrugating ring 20, arrangements are provided (as best shown in FIGS. 4 and 5) for lowering somewhat the corrugating ring 20 and its accompanying supporting and driving assembly, by pivoting same about the axis of drive shaft 43, and then, after the workpiece is in place, the corrugating ring and associated assembly is thrust up into position for working engagement with the lower side of the tubular workpiece. This may be accomplished by the use of a hydraulic or other fluid-pressure cylinder and piston means 57, the lower end of which is pivotally connected as at 58 to the base or frame part 50, and the upper end of which is connected by adjustable threaded means as at 59 to a lug 60 protruding from the periphery of the annular frame means 39. Thus when the piston means 57 is energized in one direction, it will pull the corrugating ring and the supporting and driving assembly therefor, downwardly about the axis of shaft 43, so that the corrugating ring is spaced somewhat from the path of the tube being slid onto the mandrel, and then the cylinder and piston means 57 may be actuated in the opposite direction to bring the corrugating ring up to active position. The adjustable threaded connection means 59 forming the upper connection to the cylinder and piston means 57, permits the uppermost or active position of the corrugating ring assembly to be adjusted over a considerable vertical distance to provide for engagement of the corrugating ring with tubes of different diameters. For example, if a tube of small diameter is to be corrugated, then a mandrel head asembly of appropriate size may be put onto the mandrel and the corrugating ring assembly may, by reason of the threaded adjustable means 59, be brought to a higher position such that the housing therefor will extend up to the dotted line indicated at 61 in FIG. 4, and of course with tubes of larger diameters, such as here shown at 12, the parts will assume the active position shown by full lines in FIG. 4.

The supporting ring 23, as well as the assembly of supporting and driving parts therefor, may be the same as the corresponding parts associated with the corrugating ring 22 (as just above described) except, as will be apparent from FIGS. 3-6 inclusive, the assembly of driving parts for the supporting ring 23 will extend to the righthand side of the apparatus, as shown in FIG. 6, for connection to the motor 19, whereas the corresponding parts for the corrugating ring extend to the lefthand side of FIG. 6, for connection to the motor 18. To avoid repetition of the description of the supporting and driving means for the supporting ring 23, same are simply identified by the same numerals on the drawings (but accompanied by prime marks) as the numerals which identify the corresponding parts for the corrugating ring assembly. Also, it should be noted that, in the case of the supporting ring assembly, the fluid pressure device 57' operates oppositely from the device 57. That is, when a length of tubing is being slid into place on the mandrel, the fluidpressure device 57 is operated to push the supporting ring 23 and its associated assembly upwardly out of the path of the tubing and when the machine is ready to start corrugating, then the device 57' is operated to pull supporting ring 23 down, as device 57 is operated to push the corrugating ring 22 up to active position.

Further details as to certain of the features, as well as the methods for adjusting and operating the parts, will now be explained.

It will be noted that the corrugating and supporting rollers 20 and 21 respectively on the mandrel head and as tilted in opposite directions with respect to the axis of the mandrel, will be such that the maximum diameter of these rollers, as measured perpendicularly with respect to the mandrel, is normally slightly less than the inside diameter of the plain tubing before corrugating, thus allowing the tubing to be readily slid onto the mandrel preparatory to corrugating the same. Then, when the fluid-pressure devices are actuated to thrust the corrugating ring 22 upwardly and the supporting ring 23 downwardly, these come into contact with the tubing along tangential regions, as indicated in FIGS. 9 and 10, with sufficient force so that the tubing becomes slightly oval with its sides bulging outwardly somewhat as compared with the vertical dimension. The profiles of the corrugating roller 20 and the corrugating ring 22 are such that the corrugations are normally largely impressed inwardly of the tubing; that is, the maximum outside diameter of the tube remains about the same after corrugating as before, although in actual practice the tube swells somewhat, as explained hereinafter.

The principal factors which determine the maximum diameter of the corrugating and supporting rollers 20 and 21 for a given tube diameter are: (i) the width of the roller; (ii) the helix angle at which it is skewed; and (iii) the dimensions of the grooves in the case of the corrugating roller. In practice the supporting roller 21 may be made somewhat larger than the grooved roller I 20 without interference with the tube when the latter is slid into place on the mandrel. With these factors in mind and in order that these rollers may be as large as possible and still have the desired clearance with respect to the tubing, except where actual tangential contact with the tubing takes place, they are preferably mounted eccentrically with respect to the axis of the mandrel head. This is accomplished, in the case of the corrugating roller, by the use of a bushing 64 (see FIGS. 8 and 10) encircling the shaft portion 32 and within the ball bearing assembly 30; and in the case of the supporting roller 21, by the use of a similar bushing 65. (These bushings do not appear as being eccentric in the horizontal cross-section of FIG. 8 as they do in the transverse section of FIG. 10, and the degree of eccentricity thereof is indicated also by the dotted lines 64 and 65' in FIG. 7.) Bushing 64 for the corrugating roller is eccentric in a direction so that the lower side of this roller will tangentially engage the tubular workpiece at 26, while the upper side of the roller has ample clearance with the workpiece. On the other hand, bushing 65 is eccentric in the opposite direction, so that the upper part of supporting roller 21 will engage the interior of the tubing at 27, while ample clearance remains at the bottom portion of this roller with respect to the tubing, all as will be apparent from FIG. 7. In practice, the eccentricity of bushing 64 should ordinarily be slightly greater than that of bushing 65.

While the mandrel head might be so constructed that the helix angles of the rollers thereon could be adjustable, yet for simplicity and ruggedness, it is preferable that the arrangement be constructed as shown with these angles fixed, and if for any reason different helix angles are desired, then the rollers and associated parts may be removed and replaced by others, or by another mandrel head. Even though the helix angle of these rollers is fixed, with the construction as shown, it is still possible to adjust the angular positions of the external rings 22 and 23 when it is desired to exercise some crowding or overriding effect. The calculation of the helix angle for the positions of the rollers 20, 21 is preferably based in part on theoretical considerations and in part on empirical factors. The helix angle is the function of the pitch or lead per revolution and of the pitch diameter, viz.:

pitch pitch diameter 1r Outside diameter of the uncorrugated tubing-Depth of the corrugationThe wall thickness of the tube or in the example under consideration:

O.D. "=O.D.%"

[ represents the wall thickness for 16 gauge sheet metal which may typically be used].

However, as above noted, it has been found that the corrugations do not form completely inwardly, but that due to some swelling of the tubing, the outside diameter of the corrugated tube becomes slightly greater than the outside diameter of the plain tube and as a result, it has been determined experimentally that, with an appropriate design, the corrugated pitch diameter may desirably equal the outside diameter of the plain tubing minus 0.2". Thus the formula for the helix angle of the corrugating roller 20 becomes:

Helix angle tan X 2.5 -1 Helix angle-Jan (p OD. 2) X The helix angle for the supporting roller 21 should correspond to the helix angle of the path which a fixed point would describe on the pitch diameter of the plain tube as it feeds onto the corrugating roller. Of course, the corrugating of the metal produces a shortening of the tubing. The amount of this shortening cannot be theoretically calculated, since it depends, among other factors, on the characteristics of the metal and the drawing effect thereon which takes place. With more drawing, the shortening becomes less. In order to minimize distortion of the tube metal and avoid ruptures, it is desirable to reduce the amount of drawing as much as practical and to increase the degree of shortening of the shell, if necessary.

Disregarding the shortening of the tubing, the helix angle for the supporting roller 21 should theoretically be equal to the following:

,length of plain tube fed per revolution plain tube pitch dia. 1r

however, indicates that in corrugating the tubing, it may in practice be reduced in length by some 7l0%, or in .a typical case by 7.5%, and thus the formula for the helix angle of the supporting roller 21 then becomes (assuming a wall thickness of .06 inch):

2.5 100/92.5 2.7 (plain O.D..06)1r (plain O.D..06)1r The following is an illustrative example of the helix angle calculations for a typical tube size:

Plain tube O.D.=10.0

Supporting roller 21, helix angle=tan 2.7 9.947r=4 Corrugated pitch dia.=l0.0.2=9.80" o Corrugating roller 20, helix angle=tan- 2.5/9'.801r=4 A further requirement for the smooth operation of the machine is that the tubing should be driven at the same rotational speed by both the corrugating rol'ler 20 and the supporting roller 21 acting in conjunction with the external rings 22 and 23 respectively so that the gripping either of the region 26 or 27 (FIG. 7) will not in the one case create a drag as compared with the effect at the other, causing the tube to be drawn tightly against one side or th other of the mandrel and subjecting it to unnecessary stresses. If both rings 22 and 23 are driven at the same speed, the relationship is:

tan

Experience,

tan

Pitch diameter pitch diameter of corrugating of corrugated Cos helix angle of ring 22 tubing roller 21 Pitch diameter pitch diamter' Cos helix angle of of supporting of plain tubing roller 20 ring 23 In practice the second factor on the righthand side of the above equation is so nearly equal to unity that it may be neglected. Also, for a given corrugation profile, the first factor on the righthand side varies with the size of the tubing. It is accordingly desirable to select a relationship for the diameters of th rings 22 and 23 which will be correct for approximately the minimum size of tubing to be corrugated by the machine. If necessary or desirable, however, the speeds of the drive motors for these rings may be varied more accurately to accommodate various tube diameters or different corrugation profile-s.

The provision of the corrugating means 16 and supporting means 17 with their helix angles subject to separate and independent determination or adjustment, permits the machine to be readily set up or adjusted to change, as desired, the pitch of the corrugations and at the same'time permitting control of the degree of shortening and/or twisting of the plain tube as it becomes corrugated. Also, the machine is Well adapted, upon changing the rings and rollers or the mandrel head, to produce corrugations having either similar or different pitches and profiles, or which may have various leadssuch as a singl thread or a double threadand of various sizes.

Although a particular embodiment of the invention is herein disclosed for purposes of explanation, various modifications thereof, after study of this specification, will be apparent to those skilled in the art to which the invention pertains. Reference should accordingly be had to the appended claims in determining the scope of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. Apparatus for corrugating metal tubing, comprising in combination: a mandrel having supporting means at one end and its other end being a free end onto which the metal tubing to be corrugated is adapted to be telescoped and to be corrugated as the tubing is rotated and advanced from said free end; a corrugating roller mounted on the mandrel for engaging a corrugating area on the inside surface of the tubing; a corrugating ring encircling the tubing for engaging the outer surface thereof at the region of said area; a supporting roller mounted on the m-andrel for engaging the inside surface of the tubing at a region therein on the side of the mandrel opposite said area; a supporting ring encircling the tubing for engaging the outer surface thereof at said latter region, said corrugating ring and said corrugating roller having corrugating formations thereon extending at a helix angle to the axis of the tubing corresponding approximately to the desired helix angle of the corrugations to be formed thereby on the tubing; means for mounting th corrugating ring to rotate along a plane located approximately at said angle with respect to the axis of the tubing; means for mounting said supporting ring to rotate along a plane at an approximately equal but opposite angle 'to said axis; and means for rotating said corrugating ring and said supporting ring at speeds whereby both apply components of'force for rotating and advancing the tubing at speeds which are substantially the same at the region of engagement of one ring with the tubing as at the region of engagement of the other ring with the tubing.

2. Apparatus for corrugating metal tubing, comprising in combination: a mandrel having supporting means at one end and its other end being a free end onto which the metal tubing to be corrugated is adapted to be telescoped and to be corrugated as the tubing is rotated and advanced from said free end; cooperating corrugating means for rotata'bly engaging the tubing internally and externally at one side of the mandrel; cooperating supporting means forrotatably engaging the tubing internally and externally at the opposite side of the mandrel and in advance of the corrugating means, for resisting forces reacting against the mandrel at the corrugating means and whichwould otherwise tend to deflect the mandrel; and power driven means for rotating the external corrugating means along a plane such that same applies components of force to the tubing for rotating and advancing the same, the external corrugating means comprising a ring encircling the tubing, and the internal corrugating means comprising an idler roller having a diameter as great as a major part of the diameter of the tubing.

3. Apparatus for corrugating metal tubing, comprising in combination: a mandrel having supporting means at one end and its other end being a free end onto which the metal tubing to be corrugated is adapted to be telescoped and to be corrugated as the tubing is rotated and advanced from said free end; cooperating corrugating means for rotatably engaging the tubing internally and externally at one side of the mandrel; cooperating supporting means for rotatably engaging the tubing internally and externally at the opposite side of the mandrel for resisting forces reacting against the mandrel at the corrugating means and which 'would otherwise tend to deflect the mandrel; and power driven means for rotating the external corrugating means and thereby also applying components of force to 9 Y the tubing for rotating and advancing the same, the internal corrugating means comprising an idler roller.

4. Apparatus for corrugating metal tubing, comprising in combination: a mandrel onto which the metal tubing to be corrugated is adapted to be telescoped and to be corrugated as the tubing is rotated and advanced along the mandrel; a corrugating roller mounted on the mandrel for engaging a corrugating area on the inside surface of the tubing; a corrugating ring encircling the tubing for engaging the outer surface thereof at the region of said area; a supporting roller mounted on the mandrel for engaging the inside surface of the tubing at a region therein on the side of the mandrel opposite said area; a supporting ring encircling the tubing for engaging the outer surface thereof at said latter region, said corrugating ring and said corrugating roller having corrugating formations thereon extending at a helix angle to the axis of the tubing corresponding approximately to the desired helix angle of the corrugations to be formed thereby on the tubing; means for mounting the corrugating ring and roller to rotate along a plane located approximately at said angle 'with respect to the axis of the tubing; means for mounting said supporting ring and roller to rotate along a plane at an approximately equal but opposite and slightly greater angle to said axis; and means for rotating said corrugating ring and said supporting ring at speeds whereby both apply components of force for rotating and advancing the tubing at speeds which are substantially the same at the region of engagement of one ring with the tubing as at the region of engagement of the other ring with the tubing.

5. Apparatus in accordance with the foregoing claim 4 and in which the ratio of the pitch diameter of the corrugating ring to the pitch diameter of the supporting ring substantially equals the ratio of the pitch diameter of the corrugated tubing to the pitch diameter of the plain tubing before corrugating, such pitch diameters being taken as twice the effective radius measured from the axis of the tubing to the points on the tubing where said rings engage same.

6. Apparatus for corrugating metal tubing, comprising in combination: a mandrel onto which the metal tubing to be corrugated is adapted to be telescoped and to be corrugated as the tubing is rotated and advanced along the mandrel; a corrugating roller mounted on the man-- drel eccentrically thereto for engaging a corrugating area on the inside surface of the tubing; a power rotated corrugating ring encircling the tubing eccentrically thereto for engaging the outer surface thereof at the region of said area, said corrugating ring and said corrugating roller having corrugating formations thereon extending at a helix angle to the axis of the tubing corresponding approximately to the desired helix angle of the corrugations to be formed thereby on the tubing; and means for mounting the corrugating ring and the corrugating roller to rotate along a plane located approximately at said angle with respect to the axis of the tubing.

7. Apparatus in accordance with the and in which said pitch 1 hehx angle tan pitch diameter-Xx foregoing claim 6 of the mandrel; cooperating supporting means for engaging the tubing at the opposite side of the mandrel and in advance of the corrugating means, for resisting forces reacting against the mandrel at the corrugating means and which would otherwise tend to deflect the mandrel; and power driven means for rotating the external corrugating means along a plane such that same applies components of force to the tubing for rotating and advancing the same, the external corrugating means comprising a ring encircling the tubing, and the internal corrugating means comprising a roller.

9. Apparatus for corrugating metal tubing, comprising in combination: a mandrel onto which the metal tubing to be corrugated is adapted to be telescoped and to be corrugated as the tubing is rotated and advanced along the mandrel; cooperating corrugating means for rotatably engaging the tubing internally and externally at one side of the mandrel; cooperating supporting means for rotatably engaging the tubing internally and externally at the opposite side of the mandrel for resisting forces reacting against the mandrel at the corrugating means and which would otherwise tend to deflect the mandrel; and power driven means for rotating the external corrugating means and thereby also applying components of force to the tub ing for rotating and advancing the same.

10. Apparatus in accordance with the foregoing claim 9 and in which the external corrugating means and external supporting means comprise rings encircling the tubing, and power means are provided for shifting said rings respectively to greater or lesser degrees of eccentricity with respect to the axis of the tubing for bringing same into and out of active positions for engaging the tubing.

11. Apparatus in accordance with the foregoing claim 9 and in which the external corrugating means and external supporting means comprise rings encircling the tubing and rotating in positions which are oppositely eccentric with respect to the axis of the tubing and also accompanied by means for mounting same to rotate along planes at angles to said axis which are approximately equal and opposite respectively to the desired helix angle of the corrugations to be formed on the tubing.

12. Apparatus for corrugating metal tubing comprising in combination: a mandrel onto which the tubing is adapted to be supported and to be corrugated as the tubing is rotated and advanced along the mandrel; and cooperating corrugating means for rotatably engaging the tubing internally and externally at a corrugating area at one side of the mandrel, the external corrugating means comprising a ring, means for mounting said ring and for rotating same along a plane at an angle to the axis of the mandrel, and means for adjusting said mounting and rotating means as an assembled unit to varying angles with respect to an axis which is perpendicular to the axis of the mandrel, and which is also perpendicular to a line running from said area to the axis of the mandrel, said adjusting means thereby providing for adjustment of the helix angle of the corrugations being formed.

13. Apparatus in accordance with the foregoing claim 12 and in which said rotating means comprises: a motor mounted to one side of the corrugating ring; and sprocket and chain means for driving the supporting ring from said mot-or.

14. Apparatus in accordance with the foregoing claim 12 and in which a supporting ring is mounted to encircle the tubing and to engage same on the side of the mandrel opposite from the corrugating area and in which apparatus means are also provided .for mounting said supporting ring for rotating same along a plane at an angle to the axis of the mandrel, which angle is generally opposite to the angle of the corrugating ring, and means are also provided for adjusting the mounting and rotating means for said supporting ring as an assembled unit for varying its angle to the mandrel axis.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Cochrane 72105 Spillman 72115 Prosser 72-103 Wa'lter 72--105 12 2,023,417 12/ 1935* Guarnaschelli 72115 2,664,136 12/1953 Hormberger et a1. 72103 CHARLES W. LANHAM, Primary Examiner.

W. H. JUST, Examiner. 

9. APPARATUS FOR CORRUGATING METAL TUBING, COMPRISING IN COMBINATION: A MANDREL ONTO WHICH THE METAL TUBING TO BE CORRUGATED IS ADAPTED TO BE TELESCOPED AND TO BE CORRUGATED AS THE TUBING IS ROTATED AND ADVANCED ALONG THE MANDREL: COOPERATING CORRUGATING MEANS FOR ROTATABLY ENGAGING THE TUBING INTERNALLY AND EXTERNALLY AT ONE SIDE OF THE MANDREL; COOPERATING SUPPORTING MEANS FOR ROTATABLY ENGAGING THE TUBING INTERNALLY AND EXTERNALLY AT THE OPPOSITE SIDE OF THE MANDREL FOR RESISTING FORCES REACTING AGAINST THE MANDREL AT THE CORRUGATING MEANS AND WHICH WOULD OTHERWISE TEND TO DEFLECT THE MANDREL; AND POWER DRIVEN MEANS FOR ROTATING THE EXTERNAL CORRUGATING MEANS AND THEREBY ALSO APPLYING COMPONENTS OF FORCE TO THE TUBING FOR ROTATING AND ADVANCING THE SAME. 